Parallel pipelines are frequently installed over long distances, due to the difficulty in creating or maintaining the required corridor. This implies that a release in one pipeline can seriously affect another one. The main risks associated with this domino effect are the erosive action of fluid-sand jets and the thermal action of jet fires. In this paper a survey has been performed on the accidents that have occurred, and the diverse possibilities and the associated domino sequences are analysed. The probability of occurrence of this domino effect is a function of the location of the hole, the direction of the jet, the solid angle that the jet is outlining, the diameter of both pipelines, and the distance between them. A mathematical model has been developed to estimate this probability. The model shows how the probability of domino effect decreases with the distance and diameter of the source pipe, and increases with the diameter of the target pipe. The frequency of the domino effect can be estimated from this probability and from the frequency of the initiating pipe failure plus, in the case of jet fire impingement, the probability of ignition. The frequency of the secondary pipe failure thus calculated, always higher than the individual frequency of this pipe, allows obtaining more realistic risk analysis results.
HIGHLIGHTS In parallel pipelines domino effect can have a significant influence. Domino effect will be originated by jet erosion or jet fire impingement. The domino effect probability depends on the geometric arrangement of the system. A mathematical model has been developed to estimate domino effect probability. This probability allows a more realistic estimation of failure frequencies.
ABSTRACTParallel pipelines are frequently installed over long distances, due to the difficulty in creating or maintaining the required corridor. This implies that a release in one pipeline can seriously affect another one. The main risks associated with this domino effect are erosion by fluid-sand jets and the thermal action of jet fires. In this paper a survey has been performed on the accidents that have occurred, and the diverse associated domino sequences are analyzed. The probability of occurrence of domino effect is a function of the location of the hole, the jet direction and solid angle, the diameter of both pipelines and the distance between them. A mathematical model has been developed to estimate this probability. The model shows how the probability of domino effect decreases with the distance and diameter of the source pipe, and increases with the diameter of the target pipe. Its frequency can be estimated from this probability and from the frequency of the initiating pipe failure plus, in the case of jet fire impingement, the probability of ignition. The frequency of the target pipe failure thus calculated, always higher than its individual frequency, allows a more realistic risk analysis.